Some are surprised to find that vesperbats are social creatures, as they aren't nearly as sweet as their honey-making relatives. They live in close-knit colonies of thousands of individuals, many of whom are related. When they aren't hunting, they spend considerable time grooming each other and will even feed the weaker individuals of the nest. Vesperbats communicate in many sounds, but most are too high-pitched for the human ear. Like many other bats, they hunt largely by emitting high-pitched calls and listening for the echoes. However, if angered, they'll rattle the joints in their tails to create a buzzing sound, at which point any would-be predator or trespasser should watch out. At the Keep, vesperbats are often kept all together in a communal nest, though individuals will drop by to visit the magi who raised them every so often. Despite their intimidating appearance, they actually seem to like being held and petted if they've been raised by humans, perhaps learning to see humans as very large bats. Their fur is softer than sheep's wool and when the bats shed at the start of Spring, their wool is collected as an ingredient in potions. Their venom can also be used, though it's not nearly as valuable, as it's much easier to obtain.

The much-maligned distant cousin of honeybats, vesperbats don't produce any sweet treats but they do deliver painful stings. Their barbed tails are used to kill small prey items and are thus armed with painful venom. However, this venom is harmless to most humans. The only real danger comes if someone stung is allergic or disturbs the caves where vesperbats live. They form massive nests made of chewed wood pulp of a similar consistency to paper, which when it hardens, camouflages perfectly with the rough surface of the cave walls. The nests are warm, secure places where the bats can sleep, but because of their fragility, a careless wanderer could easily bust a hole in the surface and ruin weeks of work. This is especially dangerous in the winter months when the bats sleep, so they defend their nests ferociously, swarming any intruder who wanders too close.